Biological control of gizzard shad impingement at a nuclear power plant

Biological control of gizzard shad (Dorosoma cepedianum) using predator fish species was managed to reduce impingement on cooling water intake screens at Coffey County Lake (CCL), Kansas. Long term shad and predator proportional stock densities (PSD) and body conditions (Wr) were used to characterize this fishery. Comparisons were completed between the lake’s primary productivity (mg/m³ chlorophyll-a), catch-per-unit-effort (CPUE) of young-of-year (YOY) and adult gizzard shad, and body conditions of predator species. No relationships were found between the lake’s productivity and gizzard shad densities indicating that other mechanisms control shad numbers, likely predation. Body conditions of the prevalent predator species in CCL were positively compared with the previous year’s production during a short-lived increase in shad densities. It is well documented that shad are an important food source for most predator species present in the lake. It is believed that the predator species present played a significant role in reducing YOY shad densities each year. Body conditions of predators did not indicate a surplus of a primary prey species. High shad growth rates and PSD indices promote survival of sufficient shad to adults, thus making this fishery nearly self-sustaining, and beneficial for plant operation.     

Temporal variation in size-assortative mating and male mate choice in a spider with amphisexual care

Males should be more selective when they have a high investment in reproduction, especially in species with biparental or paternal care. In this context, male mate choice can promote size-assortative mating (SAM) when (1) large males win intrasexual disputes, (2) large females are more fecund, and (3) males prefer larger females to smaller ones. In the spider Manogea porracea, males exhibit high reproductive investment by building their webs above those of females and exhibiting extended care of offspring in the absence of females. Under these circumstances, we expect the occurrence of SAM and male preference for large females. Herein, we performed observations and experiments in the field to evaluate the hypotheses that (1) M. porracea mates assortatively by size and (2) SAM is influenced by male mate choice. Furthermore, we measured variables that could affect mating patterns, the sex ratios, and densities of both sexes. Pairing in M. porracea was positively size-assortative in 2012, but not in 2013. Large males won most disputes for mates and preferred larger females, which produced more eggs. The inconsistency in detection of SAM was due to population dynamics, namely variations in sex ratio and population density across the breeding season. Furthermore, we found that the significance of male mate choice on sexual selection of body size in M. porracea strongly depends on the competition intensity for mating opportunities. The traditional sexual selection hypothesis of SAM needs to be reviewed and must include measures of competition intensity.     

Variations in stable hydrogen and oxygen isotopes in atmospheric water vapor in the marine boundary layer across a wide latitude range

The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of 8180 and 82H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature （Tair）, with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial- temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world.     

Morphological change and phenotypic plasticity in native and non-native pumpkinseed sunfish in response to competition

Non-indigenous species are oftentimes exposed to ecosystems with unfamiliar species, and organisms that exhibit a high degree of phenotypic plasticity may be better able to contend with the novel competitors that they may encounter during range expansion. In this study, differences in morphological plasticity were investigated using young-of-year pumpkinseed sunfish (Lepomis gibbosus) from native North American and non-native European populations. Two Canadian populations, isolated from bluegill sunfish (L. macrochirus) since the last glaciation, and two Spanish populations, isolated from bluegill since their introduction in Europe, were reared in a common environment using artificial enclosures. Fish were subjected to allopatric (without bluegill) or sympatric (with bluegill) conditions, and differences in plasticity were tested through a MANOVA of discriminant function scores. All pumpkinseed populations exhibited dietary shifts towards more benthivorous prey when held with bluegill. Differences between North American and European populations were observed in body dimensions, gill raker length and pelvic fin position. Sympatric treatments induced an increase in body width and a decrease in caudal peduncle length in native fish; non-native fish exhibited longer caudal peduncle lengths when held in sympatry with bluegill. Overall, phenotypic plasticity influenced morphological divergence less than genetic factors, regardless of population. Contrary to predictions, pumpkinseeds from Europe exhibited lower levels of phenotypic plasticity than Canadian populations, suggesting that European pumpkinseeds are more canalized than their North American counterparts.     

Integrated plumage colour variation in relation to body condition, reproductive investment and laying date in the collared flycatcher

The possible integration of different sexual ornaments into a composite system, and especially the information content of such ornament complexes, is poorly investigated. Many bird species display complex plumage coloration, but whether this represents one integrated or several independent sexual traits can be unclear. Collared flycatchers (Ficedula albicollis) display melanised and depigmented plumage areas, and the spectral features (brightness and UV chroma) of these are correlated with each other across the plumage. In a 5-year dataset of male and female plumage reflectance, we examined some of the potential information content of integrated, plumage-level colour attributes by estimating their relationships to previous and current year body condition, laying date and clutch size. Females were in better condition the year before they became darker pigmented, and males in better current year condition were also darker pigmented. Female pigment-based brightness was positively, while male structurally based brightness was negatively related to current laying date. Finally, the overall UV chroma of white plumage areas in males was positively associated with current clutch size. Our results show that higher degree of pigmentation is related to better condition, while the structural colour component is associated with some aspects of reproductive investment. These results highlight the possibility that correlated aspects of a multiple plumage ornamentation system may reflect together some aspects of individual quality, thereby functioning as a composite signal.     

A comparative study of an innate immune response in Lamprologine cichlid fishes

Social interactions facilitate pathogen transmission and increase virulence. Therefore, species that live in social groups are predicted to suffer a higher pathogen burden, to invest more heavily in immune defence against pathogens, or both. However, there are few empirical tests of whether social species indeed invest more heavily in immune defence than non-social species. In the current study, we conducted a phylogenetically controlled comparison of innate immune response in Lamprologine cichlid fishes. We focused on three species of highly social cichlids that live in permanent groups and exhibit cooperative breeding (Julidochromis ornatus, Neolamprologus pulcher and Neolamprologus savoryi) and three species of non-social cichlids that exhibit neither grouping nor cooperative behaviour (Telmatochromis temporalis, Neolamprologus tetracanthus and Neolamprologus modestus). We quantified the innate immune response by injecting wild fishes with phytohaemagglutinin (PHA), a lectin that causes a cell-mediated immune response. We predicted that the three highly social species would show a greater immune reaction to the PHA treatment, indicating higher investment in immune defence against parasites relative to the three non-social species. We found significant species-level variation in immune response, but contrary to our prediction, this variation did not correspond to social system. However, we found that immune response was correlated with territory size across the six species. Our results indicate that the common assumption of a positive relationship between social system and investment in immune function may be overly simplistic. We suggest that factors such as rates of both in-group and out-group social interactions are likely to be important mediators of the relationship between sociality and immune function.     

Are linear habitats in agrarian landscapes source areas of beneficial or pest rodents?

This study tested the hypotheses that populations of the montane vole Microtus montanus (a potential pest species) and deer mouse Peromyscus maniculatus (a potential beneficial species) in linear habitats will be (i) positively related to the type of vegetation (abundance and diversity of vascular plants) within and adjacent to those habitats; and (ii) correlated with population changes and productivity (reproductive performance, recruitment, and survival) in nearby apple (Malus domestica) orchards. Population dynamics of M. montanus and P. maniculatus were measured by intensive live-trapping from 2003 to 2006 in replicated hedgerows, riparian strips, and nearby orchards, in southern British Columbia, Canada. Hedgerows were borders between orchards, orchards and old fields, as well as orchards and natural forest. Contrary to hypothesis (i), M. montanus and P. maniculatus populations were not positively related to vegetation type within linear habitats and their adjacent crop and non-crop areas. Mean abundance and diversity of vegetation attributes were similar among linear habitats. Hypothesis (ii) was not supported for M. montanus populations in linear habitats since they did not correlate with population changes in nearby apple orchards, during a peak year in abundance. Populations of P. maniculatus were similar in abundance and other demographic variables among the linear habitats and apple orchards, and hence hypothesis (ii) was supported for this species.     

Changing roles of propagule, climate, and land use during extralimital colonization of a rose chafer beetle

Regardless of their ecosystem functions, some insects are threatened when facing environmental changes and disturbances, while others become extremely successful. It is crucial for successful conservation to differentiate factors supporting species’ current distributions from those triggering range dynamics. Here, we studied the sudden extralimital colonization of the rose chafer beetle, Oxythyrea funesta, in the Czech Republic. Specifically, we depicted the range expansion using accumulated historical records of first known occurrences and then explained the colonization events using five transformed indices depicting changes in local propagule pressure (LPP), climate, land use, elevation, and landscape structure. The slow occupancy increase of O. funesta before 1990 changed to a phase of rapid occupancy increase after 1990, driven not only by changes in the environment (climate and land use) but also by the spatial accumulation of LPP. Climate was also found to play a significant role but only during the niche-filling stage before 1990, while land use became important during the phase of rapid expansion after 1990. Inland waters (e.g., riparian corridors) also contributed substantially to the spread in the Czech Republic. Our method of using spatially transformed variables to explain the colonization events provides a novel way of detecting factors triggering range dynamics. The results highlight the importance of LPP in driving sudden occupancy increase of extralimital species and recommend the use of LPP as an important predictor for modeling range dynamics.     

Ecological consistency across space: a synthesis of the ecological aspects of Dromiciops gliroides in Argentina and Chile

Dromiciops gliroides is an arboreal marsupial found in the temperate forests of South America (36–43 °S). This species is the sole extant representative of the order Microbiotheria, and is a key seed disperser of many native plant species, including the keystone mistletoe Tristerix corymbosus. Here, we synthesized the current knowledge on the ecological aspects of this species, and compared the available information from Argentina and Chile. Population density (23?±?2 (mean ± SE) individual/ha) and home range (1.6?±?0.6?ha) appear to be relatively similar across a marked ecological gradient in the mainland, but lower densities (7?±?2 individual/ha) and smaller home ranges (0.26?±?0.04?ha) were detected at island sites. We detected regional variation in body condition in Chile, but there were no significant differences across a wider E-W gradient. Movement patterns fit a random walk model; such behavior might have important consequences in shaping plant’s spatial patterns. Although our data suggest that D. gliroides is more tolerant to habitat disturbance than previously thought, its incapability to disperse across non-forested areas suggests that the rapid rate of habitat loss and fragmentation that characterizes southern temperate forests likely poses a serious threat to this species. These ecological similarities are surprising given that forests studied receive dramatically different rainfall and correspond to distinct forest types. The evidence synthetized here dispels some of the myths about this species but also stresses the need for more comprehensive ecological studies across its distribution range.     

Role of winter temperature and climate change on the survival and future range expansion of the hemlock woolly adelgid (Adelges tsugae) in eastern North America

Global climate change has already affected the abundances, range limits, and interactions of many species. The hemlock woolly adelgid (Adelges tsugae), an invasive insect introduced to eastern North America from Japan, has decimated stands of eastern hemlock (Tsuga canadensis) and Carolina hemlock (T. caroliniana) from Georgia to Connecticut. However, its spread across central and northern New England has been slowed substantially by its inability to tolerate cold winter temperatures. Using data from previous lab and field studies collected over the past 17 years, including adelgid spread and overwintering mortality, we first characterize the temperature conditions that may limit adelgid spread. We then show how, in the future, rising winter temperatures due to climate change are likely to remove the conditions currently limiting adelgid spread, and facilitate the northward expansion as more suitable habitat becomes available.     

Unpacking multi-trophic herbivore-grass-endophyte interactions: feedbacks across different scales in vegetation responses to Soay sheep herbivory

Grazing can induce changes in both plant productivity and nutritional quality, which may subsequently influence herbivore carrying capacity. While research on Soay sheep (Ovis aries L.) dynamics on Hirta Island in the St. Kilda archipelago has elucidated the complexity of population drivers, including parasites, the role of herbivore-generated feedbacks as an intrinsic regulating factor remains unclear. The sheep lack large predators and every 3–9 years undergo population crashes (overcompensatory mortality). We investigated the effects of grazing on (1) sward productivity and (2) quality (toxicity) of the primary forage species, red fescue (Festuca rubra L.), which is highly infected by an alkaloid-synthesizing fungal endophyte. Grazing had a negative impact on both forage quantity and quality. At higher sheep densities, impacts on sward growth were magnified, resulting in a nonlinear relationship with plant productivity. Simultaneously, endophyte hyphal load (and by inference, toxicity) peaked close to the time of a crash. A greenhouse experiment showed that alkaloid concentration in F. rubra increased in response to artificial defoliation. We conclude that at high sheep densities, grazing-mediated reductions in productivity, together with sustained alkaloid production, are likely to influence sheep dynamics. Future research should consider the interactive effects of forage toxicity, quantity, and nutritional content.     

Impact analysis of drought, water excess and salinity on grass production in The Netherlands using historical and future climate data

The coupled SWAP-WOFOST model was used to study the effects of increasing salinity of groundwater, drought and water excess on grass production in The Netherlands. WOFOST simulates crop growth and SWAP simulates transport of water, solutes and heat in the vadose zone. The model was tested using several datasets from field experiments. We applied the models at regional scale where we quantified the impact of various groundwater salinity levels on grass growth and production using historical weather data (1971-2000). The salt concentrations in the subsoil were derived from the National Hydrological Instrument. The results show that salinity effects on grass production are limited. In wet years the excess rainfall will infiltrate the soil and reduce salt water seepage. In a next step we used future weather data for the year 2050, derived from 3 Global Circulation Models. From each model we used data from two CO₂ emission scenarios. As expected higher temperatures increased drought stress, however, the production reduction as a result of salt water in the root zone is limited. Salt stress mainly occurred when irrigation was applied with saline water. The increased CO₂ concentration in combination with the limited drought stress resulted in increasing simulated actual and potential yields. Overall conclusion for grassland in The Netherlands: drought stress is stronger than stress caused by water excess which on its turn is stronger than salinity stress. Future water demand for irrigation may increase by 11-19% and result in water scarcity if water supply is insufficient.     

杭州灰霾天气超细颗粒浓度分布特征

利用快速迁移率粒径谱仪(FMPS)对杭州2013年12月6～11日连续灰霾天气和灰霾消退过程超细颗粒进行监测,分析颗粒物浓度变化和粒径谱分布特征及其与气象的相关性.结果表明,颗粒物日变化特征为夜晚数浓度较高,凌晨数浓度开始降低,08:00和18:00上下班高峰期出现一个小峰值,体现出明显的交通源峰值,表明交通排放对大气污染影响较大.灰霾天气下颗粒物最高数浓度达到8.0×104cm-3.粒径谱呈双峰分布,峰值粒径分别为15 nm和100 nm,粒径在100 nm附近的粒子占大多数,粒子以爱根核模态和积聚模态为主,平均数量中位径CMD(count medium diameter)为85.89 nm.而在灰霾消退过程,颗粒物数浓度降低,峰值粒径向小粒径演变,粒径在100 nm附近的粒子逐渐减少,核模态粒子增多,大于积聚模态,平均CMD为58.64 nm.气象因素中能见度和风力与数浓度主要呈负相关,相关系数R分别为-0.225和-0.229,相对湿度与数浓度正相关,相关系数R为0.271,冬季大气比较稳定,水平温度与数浓度的相关性较小.研究灰霾天气数浓度分布和气象因素的综合影响对其形成机制及控制有重要意义.     

Benefits and costs of controlling three allergenic alien species under climate change and dispersal scenarios in Central Europe

Climate change is likely to exacerbate the negative effects of invasive alien species (IAS) as it will foster their further spread. This paper analyses the potential socio-economic effects of three emerging IAS (giant ragweed, Ambrosia trifida; annual wormwood, Artemisia annua; and burweed marshelder, Iva xanthiifolia), which are known to cause substantial harm to human health and to have negative effects on agricultural production. The novelty of the study consists in an integrated approach that combines several aspects of IAS research and management. We model the future spread of the study species in Central Europe by the year 2050 under several climate change, management and spread scenarios. The costs and benefits of controlling the expansion of these IAS are based on this forecast. The results show that an early and coordinated response to the spread of these IAS yields substantial net benefits under all scenarios. Under the conditions of moderate climate change (+1.5 °C), discounted net benefits range from €19 to €582 million. Assuming more severe climate change (+2.4 °C), total savings over the full period are projected to add up to €1063 million. These large socio-economic benefits provide compelling evidence that public authorities should act preventively to restrict the spread of these three IAS.     

Bird community responses to cattle stocking rates in a Pacific Northwest bunchgrass prairie

In 2006-2010, effects of four different cattle stocking rates (0, 14.4, 28.8, and 43.2 animal unit months) were compared, representing 0%, 20%, 32%, and 46% utilization of vegetation by domestic livestock, on vegetation structure (as indexed by visual obstruction), and songbird population and apparent nest density, community composition, and diversity in a Pacific Northwest bunchgrass prairie in northeastern Oregon, USA. Overall paddock-level visual obstruction decreased and structural heterogeneity increased with increasing stocking rates, and those effects carried over 1 year after grazing had ceased. Most species were able to locate nesting sites regardless of differences in visual obstruction, except western meadowlark and vesper sparrow, for which obstruction was lower in paddocks with higher stocking rates. Apparent nest density for grasshopper sparrows was negatively affected by higher stocking rates. Grazing effects on absolute songbird population density were restricted to negative effects of higher stocking rates on savannah sparrows, but this relationship was not observed until 1 year after grazing had ceased. Songbird community composition differed between control and heavily-grazed paddocks, driven by an increase in the proportion of horned larks and a decrease in the proportion of savannah sparrows in heavily-grazed paddocks from pre-treatment to post-treatment years. Bird diversity indices were unaffected by stocking rate. Negative effects of high stocking rates on densities of two species and the absence of any clear positive effect for the other three species suggest high stocking rates as applied in this experiment may not provide suitable habitat for all grassland songbirds. The absence of negative responses of density to low and moderate stocking rates suggests these grazing regimes generally provided suitable habitat for all species.     

Long-term changes of farmland game populations in a post-socialist country (Hungary)

Agricultural intensification presents a major threat to European biodiversity. This generalisation is largely based on studies from western and northern Europe. Here it is shown that the development of agriculture in a post-socialist country (Hungary) was marked by sudden changes, e.g., a 10-fold increase of fertiliser consumption in the late 1960s as a result of decision-making in the socialist command economic structures, and similar decreases after the collapse of socialism in the 1990s. Hungarian populations of two characteristic farmland species, the brown hare (Lepus europaeus) and grey partridge (Perdix perdix) are analysed and their collapse over the past four decades is related to agricultural data on production from FAO statistics. This decline was found to be negatively correlated with most measures of agricultural intensification (cereal and milk yields, number of machinery), and positively with cattle density. Multiple regression analyses of intensification measures indicated a similar pattern, although cattle density was not included into the models. Interestingly, farmland diversity in the models was negative predictor of population sizes. The sudden changes in agriculture were not indicated in the population trends of the two species. Probably, the relationship between agricultural intensification and small game species decline may not be as simple as correlation analyses indicated.     

Coadaptive changes in physiological and biophysical traits related to thermal stress in web spiders

Web spiders are considered to have expanded their habitats from dim to bright environments during the evolutionary history. Because they are sedentary predators exposed to the sun, they may have developed a suite of adaptive traits to cope with thermal stress. We examined the critical thermal maximum, spectral reflectance of solar energy by the body surface, and surface–volume ratio (SVR) for 11 spider species. Analysis of the four genera having a pair of species inhabiting both bright and dim environments showed that species in bright environments exhibited higher lethal temperatures, but spectral reflectance and SVR did not differ. Independent contrasts using the 11 species indicated that critical thermal maximum was positively correlated with spectral reflectance and spectral reflectance was negatively correlated with SVR. These results suggest that physiological tolerance to high temperatures and a biophysical mechanism to reduce heat gain evolved jointly during the history of habitat expansion in araneoid spiders.     

The role of perennial habitats for Central European farmland spiders

Spiders are important predators of insect pests. Some species invariably dominate spider communities in crop fields over large parts of Europe, and are therefore considered as “agrobionts”. It is however not clear if these species generally prefer arable habitats, or to what degree they utilize other habitats during times when crops are inhospitable. Here, spider abundances in 26 crop fields and 16 perennial habitats in Germany were compared during spring. Overall spider abundance in winter wheat was 75% lower than in perennial habitats, and species richness was reduced by 46%. Out of a total of 91 species, 73 had higher densities in perennial habitats, including the most dominant crop spiders Erigone atra and Tenuiphantes tenuis. Only one species (Oedothorax apicatus) was significantly more abundant in crops than in perennial habitats. Hence, the high dominance of most “agrobiont” species in crops was due to low densities of other species, and not to their own higher abundances. Therefore, perennial habitats adjacent to crop-fields could enhance spider populations and their potential for biological control in arable fields on a landscape level.     

Intra-specific variations of two Leymus chinensis divergence populations in Songnen Plain, northeast China

Population demography, seed production, biomassallocation, net photosynthesis and transpiration of two Leymus chinensis divergence populations and between two years in Songnenplain, northeast China were compared. Strong differences betweenthe dry 1997 and moist 1998 occurred in vegetative shoot and sexualshoot densities, sexual differentiation and tiller densities, aswell as in the lengths of inflorescence, seed numbers perinflorescence, seed weights and biomass allocation in eachpopulation respectively (P<0.01). While strong differences betweenthe two populations occurred in vegetative shoot densities, sexualshoot densities, sexual differentiation and seed weights in eachyear (P<0.01). The differences between the two populations intiller densities and in biomass allocation to sexual shoots were significant (P<0.05). But there were no significant differences between the two populations in the lengths of inflorescence, seed numbers per inflorescence and biomass allocation to rhizomes and vegetative shoots (P>0.05). Excepting the transpiration rate in the early June, the differences between the two populations in net photosynthesis and transpiration rate of vegetative shoots and sexual shoots were strongly significant in the early June and July respectively (P<0.01). Relative stable variations in population demography and physiological traits between the two populations indicated that they are divergently in the Songnen Plain.     

Intra-specific variations of two Leymus chinensis divergence populations in Songnen Plain, Northeast China

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